Ion Beam Sample Preparation Apparatus and Methods

ABSTRACT

Disclosed are embodiments of an ion beam sample preparation apparatus and methods for using the embodiments. The apparatus comprises an ion beam irradiating means in a vacuum chamber that may direct ions toward a sample, a shield blocking a portion of the ions directed toward the sample, and a shield retention stage with shield retention means that replaceably and removably holds the shield in a position. The shield has datum features which abut complementary datum features on the shield retention stage when the shield is held in the shield retention stage. The shield has features which enable the durable adhering of the sample to the shield for processing the sample with the ion beam. The complementary datum features on both shield and shield retention stage enable accurate and repeatable positioning of the sample in the apparatus for sample processing and reprocessing. A retention stage lifting means allows the creation of a loading chamber that is isolated from the main vacuum chamber where sample ion beam milling takes place. A heat sink means is configured to conduct heat away from the sample undergoing sample preparation in the ion beam.

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional utility application claims the benefit of priorfiled provisional Application No. 61/322,870 filed Apr. 11, 2010.Application No. 61/322,870 is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

DESCRIPTION OF ATTACHED APPENDIX

Not Applicable.

BACKGROUND

The present disclosure relates to the use of one or more ion beams toprepare materials for microscopic observation or spectroscopic analysis.Microscopic observational techniques include, but are not limited to,optical microscopy, scanning electron microscopy (SEM), transmissionelectron microscopy (TEM), scanning transmission electron microscopy(STEM), reflection electron microscopy (REM). Spectroscopic analysistechniques include, but are not limited to, x-ray micro-analysis,reflection electron energy-loss spectroscopy (REELS), electronback-scattered diffraction (EBSD), x-ray photoelectron spectroscopy(XPS), and Auger electron spectroscopy (AES). Materials to be viewedunder any microscopic technique may require processing to produce asample suitable for microscopic examination.

Ion beam milling of a material can produce samples that are well suitedfor microscopic examination. An ion beam irradiating device maygenerate, accelerate, and direct a beam of ions toward a sample. Theimpact of ions on the sample sputters material away from the area of ionimpact. Furthermore, the sample surface may be polished by the ion beamto a substantially smooth condition further enhancing observationalproperties of the sample. Regions of interest in the sample may beexposed and polished by the use of ion beams thus making a suitableobservational sample from the material under investigation.

Broad Ion Beam Slope-Cutting (BIBSC), also known as cross sectioncutting using broad ion beam sources or cross section polishing usingbroad ion beam sources, is a rapid method for removing sample materialto expose a smooth and substantially artifact-free cross-sectionalsurface for ultimate analysis by various microscopies andspectroscopies. A notable advantage of the BIBSC technique is high ratesof surface preparation that can exceed tens or hundreds or thousands ofsquare microns per hour, often over sample milling times of tens orhundreds of minutes.

Important considerations to users of the BIBSC technique include:reducing or minimizing the effort and time that the user is occupied inprocessing the sample; reducing or minimizing the number of steps wheredelicate samples are directly handled and at risk for damage, such asduring mounting to sample holders for processing or analysis; reducingor minimizing the time and effort the user is occupied transferring thesample into the ultimate analysis equipment (imaging or spectroscopy),and aligning the coordinates of the prepared sample region to theultimate analysis equipment prior to analysis; ensuring high quality andhigh probability of success in processing and imaging the sample;reducing or minimizing the time that the BIBSC ion milling equipment andsample mounting equipment are occupied for each sample; and ensuringhigh-quality microscopy observation of the sample during sample mountingand ultimate analysis by reducing the working distance required betweenthe sample and the objective or probe-forming lens used for observation.

Ion beam milling takes place in a suitably evacuated environment. Whilea sample may be loaded and unloaded by the user at atmospheric pressure,ion beam processing must take place under vacuum like conditions. Anear-vacuum environment that is suitable for ion beam milling of samplestakes time to establish. The time required to obtain a suitablyevacuated environment is proportional to the volume that must beevacuated prior to the commencement of ion beam milling. Embodiments ofthe present disclosure teach apparatus and methods of sample loading andprocessing that reduce the evacuated volume during sample loading andunloading, thereby enabling greater efficiencies in the processing ofsamples.

While a sample is being prepared in the ion beam, it may experienceheating. Heating may alter the sample in ways that are undesirable. Itmay be the case, for example, that heating the sample softens or meltsthe sample, thereby causing alterations in the sample that would nothappen if the temperature were maintained in a desirable range.Embodiments of the present disclosure teach apparatus, and methods ofusing that apparatus, to manage the thermal environment of a sample.Embodiments of improved thermal control over the sample may bebeneficially combined with embodiments offering improved sample loadingand processing to achieve even greater efficiencies in the processing ofsamples.

In consideration of the foregoing points, it is clear that embodimentsof the present disclosure confer numerous advantages and are thereforehighly desirable.

SUMMARY

The present disclosure is directed to ion beam sample preparationapparatus and methods for using the disclosed apparatus to preparesamples for later observation. The apparatus has features to quickly andrepeatably retain and release both unprepared samples and preparedsamples, thereby facilitating preparation of samples in the ion beamapparatus and also facilitating the observation of the prepared samplesin an observation apparatus. Features of the disclosure enable accurateand repeatable positioning of the sample both within the ion beam samplepreparation apparatus and within observation apparatus later used forobserving prepared samples. Sample loading and processing features ofthe present disclosure work to reduce the volume requiring evacuationafter sample loading. Sample loading and processing features also workto maintain a vacuum-like environment in a substantial portion of thevacuum chamber, even while the sample is being loaded at atmosphericpressure. Thermal management features of the present disclosure work tomanage the thermal environment of the sample being prepared. Thetemperature of the sample undergoing ion beam sample preparation maythereby be influenced by the thermal environment created by theapparatus.

An embodiment according to the present disclosure of an apparatus forion beam sample preparation comprises: an ion beam irradiating meansdisposed in a vacuum chamber and directing an ion beam toward a shieldretention stage; the shield retention stage being disposed in the vacuumchamber; said shield retention stage comprising: a first datum feature;a second datum feature; a shield retention means having at least ashield releasing position and a shield retaining position; a retentionstage lifting means coupled to said shield retention stage andconfigured to move said shield retention stage between a retention stageloading position and a retention stage processing position,characterized in that when the retention stage lifting means is in saidretention stage loading position, a substantially vacuum-tight loadingchamber is created between the shield retention stage and a portion ofthe vacuum chamber, and further characterized in that when the retentionstage lifting means is in said retention stage loading position, asubstantially vacuum-tight seal is created between the loading chamberand the portion of the vacuum chamber in which the ion beam irradiatingmeans is disposed; a lift drive coupled to said retention stage liftingmeans and operable to move said retention stage lifting means betweensaid retention stage loading position and said retention stageprocessing position; a removable and replaceable chamber cover disposedto allow access to said loading chamber when said retention stagelifting means is held in said retention stage loading position,characterized in that said chamber cover provides a substantiallyvacuum-tight seal when in place on said vacuum chamber; a shield havingat least a rigid planar portion, removably and replaceably held in saidshield retention stage, said shield further comprising: a proximalsample surface configured to durably adhere the sample to the shield; afirst shielding surface disposed in the path of the ion beam andpositioned to shield a portion of the ion beam directed at the samplewhen said shield is held in the shield retaining position of the shieldretention means and the retention stage lifting means is held in theretention stage processing position; a third datum feature formedintegrally with said shield, wherein said shield retention means in saidshield retaining position urges said third datum feature to abut saidfirst datum feature; and a fourth datum feature formed integrally withsaid shield, wherein said shield retention means in said shieldretaining position urges said fourth datum feature to abut said seconddatum feature; a vacuum pump means operably connected to both a firstpumping manifold and a second pumping manifold, wherein the firstpumping manifold is configured to evacuate said vacuum chamber, andwherein the second pumping manifold is configured to evacuate saidloading chamber when said retention stage lifting means is in saidretention stage loading position.

In a related embodiment of the ion beam sample preparation apparatus,the shield retention stage further comprises a fifth datum feature, andthe shield further comprises a sixth datum feature formed integrallywith the shield, wherein the shield retention means in said shieldretaining position urges said sixth datum feature to abut said fifthdatum feature.

In a related embodiment of the ion beam sample preparation apparatus,the first shielding surface meets said proximal sample surface at anangle of less than about 90 degrees and more than about 80 degrees.

In a related embodiment of the ion beam sample preparation apparatus,the first shielding surface meets said proximal sample surface at anangle of less than about 87 degrees and more than about 83 degrees.

In a related embodiment of the ion beam sample preparation apparatus,the first shielding surface is made of non-magnetic material having lowsputtering-yield.

In a related embodiment of the ion beam sample preparation apparatus, atleast a portion of the first shielding surface is made of tantalum ortitanium.

In a related embodiment of the ion beam sample preparation apparatus,the third datum feature is a datum surface and at least a portion ofsaid datum surface is coextensive with at least a portion of saidproximal sample surface.

In a related embodiment of the ion beam sample preparation, the proximalsample surface has at least one recessed portion configured for theflowing of adhesive between the shield and the sample.

In a related embodiment of the ion beam sample preparation apparatus,the shield further comprises a sample clamping means coupled to theshield and configured to hold the sample against said proximal samplesurface.

In a related embodiment of the ion beam sample preparation apparatus,the shield further comprises: a second shielding surface having aportion disposed in the path of a portion of the ion beam; a shield edgeformed where the first shielding surface meets the proximal samplesurface; and a visible alignment mark on the second shielding surface,configured such that the location of said alignment mark is in apredetermined relationship to the region where the ion beam impinges onsaid shield edge when said shield is held in the shield retainingposition of the shield retention means.

In a related embodiment of the ion beam sample preparation apparatus,the shield is made of a cladding material joined to a core material suchthat a portion of the cladding material forms at least a portion of thefirst shielding surface, and a portion of the core material forms thethird and fourth datum features of the shield. In a related embodiment,the cladding material is a non-magnetic material having lowsputtering-yield.

Another embodiment of the present disclosure is directed to an apparatusfor ion beam sample preparation which comprises: an ion beam irradiatingmeans disposed in a vacuum chamber and directing an ion beam toward ashield retention stage; the shield retention stage being disposed in thevacuum chamber; said shield retention stage comprising: a first datumfeature; a second datum feature; a shield retention means having atleast a shield releasing position and a shield retaining position; aretention stage lifting means coupled to said shield retention stage andconfigured to move said shield retention stage between a retention stageloading position and a retention stage processing position,characterized in that when the retention stage lifting means is in saidretention stage loading position, a substantially vacuum-tight loadingchamber is created between the shield retention stage and a portion ofthe vacuum chamber, and further characterized in that when the retentionstage lifting means is in said retention stage loading position asubstantially vacuum-tight seal is created between the loading chamberand the portion of the vacuum chamber in which the ion beam irradiatingmeans is disposed; a lift drive coupled to said retention stage liftingmeans and operable to move said retention stage lifting means betweensaid retention stage loading position and said retention stageprocessing position; a removable and replaceable chamber cover disposedto allow access to said loading chamber when said retention stagelifting means is held in said retention stage loading position,characterized in that said chamber cover provides a substantiallyvacuum-tight seal when in place on said vacuum chamber; a shield havingat least a rigid planar portion, removably and replaceably held in saidshield retention stage, said shield further comprising: a proximalsample surface configured to durably adhere the sample to the shield; afirst shielding surface disposed in the path of the ion beam andpositioned to shield a portion of the ion beam directed at the samplewhen said shield is held in the shield retaining position of the shieldretention means and the retention stage lifting means is held in theretention stage processing position; a third datum feature formedintegrally with said shield, wherein said shield retention means in saidshield retaining position urges said third datum feature to abut inthermally conductive contact with said first datum feature; and a fourthdatum feature formed integrally with said shield, wherein said shieldretention means in said shield retaining position urges said fourthdatum feature to abut said second datum feature; a vacuum pump meansoperably connected to both a first pumping manifold and a second pumpingmanifold, wherein the first pumping manifold is configured to evacuatesaid vacuum chamber, and wherein the second pumping manifold isconfigured to evacuate said loading chamber when said retention stagelifting means is in said retention stage loading position; a firstthermal transfer member in thermally conductive contact with the shieldretention stage; and a heat sink means configured to conduct heat awayfrom said first thermal transfer member.

In a related embodiment of the ion beam sample preparation apparatus,the heat sink means is configured to use nitrogen to conduct heat awayfrom the first thermal transfer member.

In a related embodiment of the ion beam sample preparation apparatus,the shield is made of a cladding material joined to a core material suchthat a portion of the cladding material forms at least a portion of thefirst shielding surface, and a portion of the core material forms thethird and fourth datum features of the shield. In a related embodiment,the core material has high thermal conductivity. In a related embodimentthe core material comprises copper.

Another embodiment of the present disclosure is directed to an apparatusfor ion beam sample preparation which comprises: an ion beam irradiatingmeans disposed in a vacuum chamber and directing an ion beam toward ashield retention stage; the shield retention stage being disposed in thevacuum chamber; said shield retention stage comprising: a first datumfeature; a second datum feature; a shield retention means having atleast a shield releasing position and a shield retaining position; aretention stage lifting means coupled to said shield retention stage andconfigured to move said shield retention stage between a retention stageloading position and a retention stage processing position,characterized in that when the retention stage lifting means is in saidretention stage loading position, a substantially vacuum-tight loadingchamber is created between the shield retention stage and a portion ofthe vacuum chamber, further characterized in that when the retentionstage lifting means is in said retention stage loading position, asubstantially vacuum-tight seal is created between the loading chamberand the portion of the vacuum chamber in which the ion beam irradiatingmeans is disposed, and further characterized in that when the retentionstage lifting means is in said retention stage loading position, saidshield retention stage is in thermally conductive contact with a portionof said vacuum chamber; a lift drive coupled to said retention stagelifting means and operable to move said retention stage lifting meansbetween said retention stage loading position and said retention stageprocessing position; a removable and replaceable chamber cover disposedto allow access to said loading chamber when said retention stagelifting means is held in said retention stage loading position,characterized in that said chamber cover provides a substantiallyvacuum-tight seal when in place on said vacuum chamber; a shield havingat least a rigid planar portion, removably and replaceably held in saidshield retention stage, said shield further comprising: a proximalsample surface, configured to durably adhere the sample to the shield; afirst shielding surface, disposed in the path of the ion beam, andpositioned to shield a portion of the ion beam directed at the samplewhen said shield is held in the shield retaining position of the shieldretention means and the retention stage lifting means is held in theretention stage processing position; a third datum feature formedintegrally with said shield, wherein said shield retention means in saidshield retaining position urges said third datum feature to abut inthermally conductive contact said first datum feature; and a fourthdatum feature, formed integrally with said shield, wherein said shieldretention means in said shield retaining position urges said fourthdatum feature to abut said second datum feature; a vacuum pump meansoperably connected to both a first pumping manifold and a second pumpingmanifold, wherein the first pumping manifold is configured to evacuatesaid vacuum chamber, and wherein the second pumping manifold isconfigured to evacuate said loading chamber when said retention stagelifting means is in said retention stage loading position; a thermaltransfer member, disposed so that said thermal transfer member is inthermally conductive contact with the shield retention stage when saidretention stage lifting means is held in said retention stage processingposition, and further disposed so that said thermal transfer member isnot in thermally conductive contact with the shield retention stage whensaid retention stage lifting means is held in said retention stageloading position; and a heat sink means configured to conduct heat awayfrom said thermal transfer member.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1A shows a schematic cross-sectional view of an ion beam samplepreparation apparatus, additionally comprising retention stage liftingmeans according to an embodiment of the present disclosure. FIG. 1Ashows the apparatus in a retention stage loading position prior toloading a shield in the shield retention stage.

FIG. 1B shows a schematic cross-sectional view of an ion beam samplepreparation apparatus, additionally comprising retention stage liftingmeans according to an embodiment of the present disclosure. FIG. 1Bshows the apparatus in a retention stage loading position after loadinga shield in the shield retaining position.

FIG. 1C shows a schematic cross-sectional view of an ion beam samplepreparation apparatus, additionally comprising retention stage liftingmeans according to an embodiment of the present disclosure. FIG. 1Cshows the apparatus in a sample loading position after loading a shieldin the shield retention stage, and after the fitting of a chamber coverto the loading chamber.

FIG. 2 shows a schematic cross-sectional view of an ion beam samplepreparation apparatus, additionally comprising retention stage liftingmeans according to an embodiment of the present disclosure. FIG. 2 showsthe apparatus in a retention stage processing position.

FIG. 3A shows a perspective view of a shield retention stage retaining ashield with a sample durably adhered to the shield. The figure alsoshows the cross section plane used for FIG. 3B.

FIG. 3B shows a cross-sectional view of the shield retention stage ofFIG. 3A with shield retention means in a shield retaining position.

FIG. 4 shows a cross section similar to that of FIG. 3B, except thatFIG. 4 shows the cross section with the shield retention means in ashield releasing position.

FIG. 5A shows a perspective view of a shield retention stage accordingto the present disclosure, indicating a cross-sectional plane for FIG.5B.

FIG. 5B shows a perspective sectional view of the shield retention stageof FIG. 5A, with the shield positioned in the shield retaining position.

FIG. 6 shows an exploded perspective section view of the shield andshield retention stage of FIG. 5B. Datum features of both the shield andthe shield retention stage are made visible in this view.

FIGS. 7A and 7B show perspective views of a shield according toembodiments of the present disclosure, viewed from the ion beam side ofthe shield.

FIGS. 8A and 8B show perspective views of a shield according toembodiments of the present disclosure, viewed from the proximal sampleside of the shield.

FIG. 9 shows a perspective view of another shield according to thepresent disclosure, viewed from the ion beam side of the shield andhaving a visible alignment feature.

FIG. 10 shows a perspective view of another shield according to thepresent disclosure, viewed from the proximal sample side of the shieldand having a recessed portion to facilitate the flow of adhesive underthe sample.

FIGS. 11A and 11B show perspective views of a shield with a durablyadhered sample, both before (FIG. 11A) and after (FIG. 11B) preparationin an ion beam sample preparation thermal management apparatus accordingto the present disclosure.

FIGS. 12A and 12B show an embodiment of a shield with integrated sampleclamping means, according to an embodiment of the present disclosure.

FIG. 13A and FIG. 13B show schematic views of embodiments of a shieldcomprising core material and cladding material.

FIG. 14A shows a schematic cross-sectional view of an ion beam samplepreparation apparatus, having both a shield retention stage liftingmeans and a heat sink means for temperature control of the sample. InFIG. 14A the shield retention stage lifting means is shown in a sampleloading position and the shield retention means is shown in the shieldretaining position.

FIG. 14B shows a schematic cross-sectional view of the same apparatus asin FIG. 14A. In FIG. 14B the shield retention stage lifting means isshown in the sample processing position.

FIG. 15A shows a schematic cross-sectional view of another embodiment ofan ion beam sample preparation apparatus, having both a shield retentionstage lifting means and a heat sink means for temperature control of thesample. In FIG. 15A the shield retention stage lifting means is shown ina sample loading position and the shield retention means is shown in theshield retaining position.

FIG. 15B shows a schematic cross-sectional view of the same apparatus asin FIG. 15A. In FIG. 15B the shield retention stage lifting means isshown in the sample processing position.

LIST OF REFERENCE NUMBERS APPEARING IN THE FIGURES

2—ion beam sample preparation apparatus

8—sample

10—vacuum chamber

16—loading chamber

18—chamber cover

20—ion beam irradiating means

22—central ion beam axis

40—shield retention stage

42—shield retention means

42 a—shield retention means first member

42 b—shield retention means second member

46—shield retaining position

48—shield releasing position

56—vacuum seal

60—shield

61—shielding surface

61 a, 61 b, etc.—first shielding surface, second shielding surface, etc.

62—proximal sample surface

63—shield edge

64—recessed portion

65—visible alignment mark

66—core material

67—cladding material

68—sample clamping means

70 a, 70 b, 70 c, 70 d, 70 e, 70 f—first datum feature, second datumfeature, third datum feature, fourth datum feature, fifth datum feature,sixth datum feature.

72—datum surface

80—thermal transfer member

84—heat sink means

90—vacuum pump means

92—pumping manifold

92 a, 92 b, etc.—first pumping manifold, second pumping manifold etc.

100—retention stage lifting means

102—lift drive

104—retention stage loading position

106—retention stage processing position

DESCRIPTION

The Broad Ion Beam Slope-Cutting (BIBSC) sample preparation procedurecan be described as a series of process steps, p1-p5:

-   -   p1) Aligning the desired region of the sample to be processed to        a usable portion of an ion shield;    -   p2) Aligning the sample and shield in the BIBSC ion-milling        system such that the desired region of the sample can be        processed by the ion beam or beams;    -   p3) Evacuating the ion-milling system to vacuum levels        appropriate for ion beam milling;    -   p4) Performing the ion-milling operation or operations,        sometimes using a process monitoring step such as in situ        light-microscopy imaging to verify sufficient cut depth and        quality of the cross section;    -   p5) Venting of the BIBSC ion-milling equipment and removal of        the sample from the equipment.

The analysis of prepared BIBSC sample can be described as a series ofprocess steps, p6-p9:

-   -   p6) Introduction of the sample to the ultimate analysis        microscope and initializing the microscope so that analysis can        commence;    -   p7) Finding the location of the prepared cross-sectional surface        by adjusting any number of the microscope's translation stages,        tilt stages, and rotation stages so that the desired area can be        imaged;    -   p8) Performing the desired microscopic or spectroscopic        analyses;    -   p9) Removing the sample from the microscope;    -   p10) After analyzing the sample, a decision may be made to        reprocess the sample to change the cut depth, position, or        angle—traditionally requiring a repeat of p1-p9.

Embodiments of the present disclosure uniquely permit certainefficiencies and capabilities in the processing and subsequentobservation and analysis of BIBSC produced samples. Beneficial features,functions, and aspects of the present disclosure include, but are notlimited to:

-   -   1. Datum features on the shield, shield retention device in the        sample-to-shield mounting apparatus, shield retention device in        the BIBSC ion-mill, shield retention device in the ultimate        analysis equipment allow significant time efficiencies in        processing steps p1, p2 and p7;    -   2. The integral nature of the sample durably adhered to the        shield, and to a lesser extent with the sample merely clamped to        the shield, allows greater certainty in ensuring alignment of        the shield to the sample remains consistent during p4 even over        long time-scales and changes in temperature, whereas quality of        the cross section cutting process is reduced if this precision        alignment is not maintained;    -   3. The integral nature of the sample durably adhered to the        shield in processing step p1 eliminates the requirement for        expensive and sizable fixturing apparatus to maintain their        spatial relationship together throughout the milling operation,        and enables multiple samples to be prepared in advance of        milling without multiple fixturing apparatus;    -   4. The integral nature of the sample durably adhered or clamped        to the shield eliminates the requirement for dismounting the        sample from the shield prior to observation in a microscope,        even in cases where the smallest working distances between        imaging objective and sample are employed. This permits        reduction of both time and risk of damage to the sample during        sample remounting in processing step p6;    -   5. In the case where reprocessing the sample as in step p10 is        performed, the integral nature of the sample durably adhered or        clamped to the shield can eliminate the need for steps p1 and p2        entirely, which significantly reduces processing time and risk        of damage to the sample during sample remounting; and    -   6. In the case where reprocessing the sample as in step p10 is        performed, the integral nature of the sample durably adhered or        clamped to the shield allows different cross-sectional planes to        be cut very close to the originally cut cross-sectional plane by        varying the angle of ion beam impinging on the sample and        shield.

Turning now to FIG. 1A, illustrated is a schematic cross-sectional viewof an embodiment of an ion beam sample preparation apparatus 2. Theembodiment of FIG. 1A is shown comprising: a vacuum chamber 10 in whicha sample may be prepared by an ion beam irradiating means 20; aremovable and replaceable chamber cover 18, which, when removed fromchamber 10, allows access for sample and shield loading; a first pumpingmanifold 92 a and a vacuum pump means 90, which together bring vacuumchamber 10 to vacuum levels appropriate for ion beam milling; a shieldretention stage 40 and a shield retention means 42, the shield retentionmeans 42 being shown in FIG. 1A in a shield releasing position 48; aretention stage lifting means 100, which is coupled to said shieldretention stage 40; a lift drive 102 operably coupled to said retentionstage lifting means 100 wherein the shield retention stage may be liftedinto a retention stage loading position 104, and vacuum seal 56 whichallows the retention stage lifting means to move up and down whilemaintaining vacuum seal between vacuum chamber 10 and the outsideatmosphere. When shield retention stage 40 is raised to retention stageloading position 104, a loading chamber 16 is created. When in theretention stage loading position 104, vacuum sealing features of theshield retention stage 40 engage with vacuum sealing features of thevacuum chamber 10, and function to isolate said vacuum chamber from theoutside atmosphere.

FIG. 1B shows the same embodiment as FIG. 1A, additionally showing ashield 60 with a sample 8 durably adhered to the shield has been placedin the shield retention stage 40 and is held in the stage by shieldretention means 42 in a shield retaining position.

FIG. 1C shows the same embodiment as FIG. 1B, additionally showing thatchamber cover 18 has been placed on vacuum chamber 10 to seal loadingchamber 16 from the outside atmosphere. In a preferred embodiment, whenchamber cover 18 is in place to seal the loading chamber from theoutside atmosphere, the volume of loading chamber 16 is substantiallysmaller than the volume of vacuum chamber 10. When the apparatus isconfigured as in FIG. 1C, second pumping manifold 92 b and pumping means90 may be used to evacuate loading chamber 16 in preparation forlowering the shield retention stage into the retention stage processingposition. When the loading chamber has been evacuated to suitable vacuumlevels, the retention stage lifting means may be activated to lower theshield retention stage in preparation for ion beam milling of thesample.

FIG. 2 shows the same embodiment as FIG. 1C. In FIG. 2 retention stagelifting means 100 and lift drive 102 have operated to lower the shieldretention stage 40 into a retention stage processing position 106. Theembodiment of FIG. 2 is shown comprising ion beam irradiating means 20,which directs an ion beam having a central ion beam axis 22 towardsample 8, and a shield 60, which shields at least a portion of sample 8from at least a portion of the ion beam. After sample 8 has beenprepared in the ion beam, the sequence of steps illustrated in figuresFIG. 1A, FIG. 1B, FIG. 1C, and FIG. 2 may be reversed to raise thesample to the retention stage loading position, remove chamber cover 18,and remove the shield and sample combination for observation in amicroscope.

With continuing reference to FIG. 2, the ion beam preferably comprisesnoble gas ions. Elements used for the ion beam may include, but are notlimited to: Argon, Xenon, and Krypton. The ion beam may also comprise amixture of ions and neutrals. When in retention stage processingposition 106, the shield retention stage 40 is disposed in vacuumchamber 10 in a predetermined position and orientation with respect tocentral ion beam axis 22.

In a preferred embodiment of shield 60, a material with good thermalconductivity may be used to improve thermal transfer between shield andthe shield retention stage, said material including, but not limited to,a substantially non-magnetic metal. In another preferred embodiment ofshield 60, a material with good thermal conductivity can be used as acore material 66 to improve thermal transfer between shield and theshield retention stage, and a substantially non-magnetic material withlow sputtering-yield may be used as a cladding material 67 over the corematerial, whereby the cladding material forms at least part of theshielding surface 61 of shield 60. Figures FIG. 13A and FIG. 13Billustrate two different embodiments of shield 60, wherein eachembodiment is shown comprising a combination of core material 66 andcladding material 67.

FIG. 3A shows a perspective view of shield retention stage 40 on whichsample 8 has been durably adhered to shield 60 prior to placing theshield and sample combination in a shield retaining position in shieldretention stage 40. Shield 60 has a shielding surface 61, which ispositioned in relation to sample 8 to shield at least a portion of saidsample 8 from at least a portion of the ion beam. Also shown in FIG. 3Ais a section line indicating the section view shown in FIG. 3B.

FIG. 3B shows a section view illustrating the position and function ofthe shield retention means, which is part of shield retention stage 40.FIG. 3B shows an embodiment of the shield retention means in shieldretaining position 46, the shield retention means comprising a shieldretention means first member 42 a and a shield retention means secondmember 42 b. Shield retention means first member 42 a urges shieldretention means second member 42 b against shield 60. The action ofshield retention means first member also urges shield 60 against shieldretention stage 40, and thereby maintains the position of shield 60within shield retention stage 40 while the sample is prepared by ionbeam. An embodiment of the shield retention means may comprise a springfor shield retention means first member 42 a and a solid member asshield retention means second member 42 b configured to slide within acavity in shield retention stage 40.

FIG. 4 shows a view from the same sectional plane as in FIG. 3B.However, in FIG. 4 the shield and sample have been removed to show ashield releasing position 48 of shield retention means. By means of thetwo positions provided by shield retention means, namely shieldretaining position 46 as shown in FIG. 3A and FIG. 3B, and shieldreleasing position 48, as shown in FIG. 4, a shield may be removably andreplaceably secured in shield retention stage 40. A sample that has beendurably adhered to shield 60 may be processed, removed, and thenreprocessed by simply placing it in the shield retaining position andpreparing the sample again in the ion beam.

FIG. 5A shows a perspective view of shield retention stage 40, on whichshield 60 is retained, wherein said shield has a shielding surface 61.FIG. 5A also shows a sectional plane used for FIG. 5B.

FIG. 5B shows a sectional perspective view illustrating physicalfeatures of both shield 60 and shield retention stage 40, whichfacilitate accurate and repeatable positioning of the shield withrespect to the shield retention stage. The positioning of shield 60assures that shielding surface 61 and shield edge 63 are accuratelypositioned and accurately oriented with respect to the shield retentionstage and are positioned with respect to central ion beam axis 22 tointercept at least a portion of the ion beam directed toward the sample.

FIG. 6 shows a sectional perspective view as in FIG. 5B in whichpreferred embodiments of both shield 60 and shield retention stage 40have a plurality of datum features 70 a, 70 b, 70 c, 70 d, 70 e, and 70f. In the exploded view shown in FIG. 6, shield 60 has been removed fromshield retention stage 40 and the shield is turned to expose a proximalsample surface 62 upon which a sample may be durably adhered prior tosample preparation by the ion beam. The plurality of datum features 70a, 70 b, 70 c, 70 d, 70 e, and 70 f is provided on both shield 60 andshield retention stage 40 and the datum features enable accurate andrepeatable positioning of the shield 60 with respect to the shieldretention stage 40. Datum features 70 b, 70 d, and 70 f on the shieldare shaped and positioned such that when they are caused to abutcomplementary datum features 70 a, 70 c, and 70 e on the shieldretention stage the shield may be held in a predetermined position and apredetermined orientation with respect to the central ion beam axis 22.Shield retention means 42 assures that datum features 70 b, 70 d, and 70f of shield 60 abut the corresponding datum features 70 a, 70 c, and 70e of the shield retention stage 40 when the shield is held in the shieldretaining position. Shield edge 63, also visible in FIG. 6, is alsocaused to be in a predetermined position and predetermined orientationwhen the shield is held in the shield retaining position.

Datum features are arranged in pairs such that a datum feature on theshield has a corresponding datum feature on the shield retention stage.In FIG. 6 one such pair of datum features is datum feature 70 a on theshield retention stage and datum feature 70 b on the shield. Anotherpair of datum features shown in FIG. 6 is datum feature 70 c on theshield retention stage and datum feature 70 d on the shield. Anotherpair of datum features shown in FIG. 6 is datum feature 70 e on theshield retention stage and datum feature 70 f on the shield. When theshield is in the shield retaining position, the shield retention meansacts to urge the pairs of datum features to abut, thereby constrainingthe position of the shield with respect to the position of the shieldretention stage. Datum features may be datum surfaces, as is shown inthe preferred embodiment of FIG. 6, or they may be datum edges, datumvertices, or combinations of datum surfaces, datum edges, and datumvertices.

Turning now to figures FIG. 7A, FIG. 7B, FIG. 8A, FIG. 8B, FIG. 9, andFIG. 10, shown are various features and embodiments of shield 60according to the present disclosure.

FIG. 7A is a perspective view of a shield showing a first shieldingsurface 61 a, a second shielding surface 61 b, and shield edge 63. Ionsfrom the ion beam irradiating means that are blocked by the shield, and,in particular, the ions that are blocked by first shielding surface 61 aare prevented from milling the sample. Ions not blocked by the shieldmay be used to prepare the sample for observation and analysis. When theion beam is operating, ions may or may not impact second shieldingsurface 61 b. Whether ions do impact second shielding surface 61 bdepends on a number a factors including, but not limited to: the size ofthe ion beam; the angle at which the ion beam is directed; and theposition at which the ion beam is directed. It is a preferred embodimentof the shield that second shielding surface 61 b be made of the samematerial as first shielding surface 61 a. In preferred embodimentsshield 60 is a generally planar rigid member, having one or moreshielding surfaces that are smooth and may be polished, having a datumsurface and at least an additional datum feature for facilitatingaccurate placement within the shield retention stage. Preferredmaterials for the shield are non-magnetic metals with low sputter yieldincluding, but not limited to, tantalum or titanium. Lower costembodiments of shield 60 may comprise core material 66 for the majorityof the shield and cladding material 67 used for the shielding surfaces.Preferred core materials include, but are not limited to, copper.Preferred cladding materials include, but are not limited to, tantalumor titanium. Figures FIG. 13A and FIG. 13B illustrate two differentembodiments of a shield 60, wherein each embodiment is shown comprisinga combination of core material 66 and cladding material 67.

FIG. 7B shows the same shield as shown in FIG. 7A, but from a differentangle, thereby illustrating the position and nature of a plurality ofdatum features 70 d and 70 f.

FIG. 8A shows the same shield as shown in FIG. 7A and FIG. 7B. FIG. 8Ashows a perspective view of shield 60 from the side of the shieldclosest to the sample during ion beam sample preparation. Proximalsample surface 62 may be used to adhere the sample material to beprepared in the apparatus. Datum surface 72 is a datum feature that is asurface. In a preferred embodiment, at least a portion of proximalsample surface 62 may be coextensive with at least a portion of datumsurface 72. Shield edge 63 is formed by the intersection of firstshielding surface 61 a and proximal sample surface 62. The angle betweenfirst shielding surface 61 a and proximal sample surface 62 has animpact on the quality of milling performed on the sample by the ionbeam. A preferred embodiment is achieved when said first shieldingsurface 61 a meets said proximal sample surface 62 at an angle of lessthan about 90 degrees and more than about 80 degrees. An even morepreferred embodiment is achieved when said first shielding surface 61 ameets said proximal sample surface 62 at an angle of less than about 87degrees and more than about 83 degrees.

FIG. 8B shows the same shield as shown in FIG. 8A, but from a differentangle, thereby illustrating the position and nature of a plurality ofdatum features 70 d and 70 f, and datum surface 72, present on shield60.

FIG. 9 shows a perspective view of shield 60 having first shieldingsurface 61 a, second shielding surface 61 b, shield edge 63, andadditionally comprising a visible alignment mark 65. When the shield isheld in the shield retaining position, the visible alignment mark ispositioned so that it indicates the approximate location where a portionof the ion beam will pass over shield edge 63 and impact the sample whenthe shield edge is substantially perpendicular to the central ion beamaxis.

FIG. 10 shows a perspective view of shield 60 from the side of theshield closest to the sample during ion beam sample preparation.Proximal sample surface 62 may be used to adhere the sample material tothe shield prior to ion beam sample preparation in the apparatus.Recessed portion 64 provides a recessed portion of proximal samplesurface 62 useful for flowing adhesive under the sample, therebyfacilitating the durable adhering of sample to shield. Preferredmaterials used to adhere the sample to the shield include, but are notlimited to: UV cured glue, light cured glue, superglue, silver paint,and wax.

Turning now to FIG. 11A, shown is a perspective view of shield 60,shielding surface 61, sample 8 durably adhered to the shield, andvisible alignment mark 65. FIG. 11A depicts the sample prior to ion beampreparation. FIG. 11B is a perspective view of the same objects depictedin FIG. 11A. However, FIG. 11B represents the sample after ion beamsample preparation. Shielding surface 61 intercepts a portion of the ionbeam, which travels along central ion beam axis 22. A portion of sample8 is sputtered away by the ion beam during sample preparation, therebyexposing a portion of the sample lying in the plane defined by shieldedge 63 and central ion beam axis 22. A sample prepared in this way willbe suitable for observation or analysis with a variety of microscopic orspectroscopic techniques, particularly those requiring a highly polishedplanar surface.

FIG. 12A and FIG. 12B illustrate another embodiment of shield 60, inwhich a sample clamping means 68 is formed integrally with the shield onthe proximal sample surface 62. FIG. 12A depicts this shield prior toclamping a sample, while FIG. 12B depicts this shield after sample 8 hasbeen secured to the shield by means of sample clamping means 68. Inanother embodiment, sample clamping means 68 may be formed separatelyand then coupled to the shield prior to clamping the sample. Adhesivemay be applied between the sample clamping means and the sample tofurther ensure the sample does not move with respect to the shield.

Use of the apparatus shown in FIG. 1A, FIG. 1B, FIG. 1C, and FIG. 2 mayproceed with reference to the following steps. Outside of the vacuumchamber, a sample may be durably adhered to a shield. The shieldretention stage may be moved to the retention stage loading position,thereby creating a loading chamber that is vacuum-tight with respect tothe portion of the vacuum chamber in which the ion beam irradiatingmeans is disposed. Then the loading chamber may be pressurized toatmospheric pressure by operation of the vacuum pump means through thesecond pumping manifold. The chamber cover may then be removed. With thechamber cover removed, the shield and sample combination may be securedin the shield retaining position of the shield retention stage. Thechamber cover may then be replaced. With the chamber cover in place onthe vacuum chamber the vacuum pump means may be operated to evacuate theloading chamber through the second pumping manifold thereby obtainingvacuum levels substantially below atmospheric pressure. The retentionstage lifting means and lift drive may then be operated to move theshield retention stage to the retention stage processing position. Thevacuum pump means may operate throughout the loading process through thefirst pumping manifold to maintain vacuum levels in the vacuum chamber.Once the sample and shield have been moved into the retention stageprocessing position, the ion beam irradiating means may then be operatedto prepare the sample. When the sample has been prepared to the extentdesired by the user of the apparatus, the ion beam irradiating means maybe turned off. Then the retention stage lifting means and lift drive mayoperate to move the shield retention stage back to the retention stageloading position. With the vacuum tight loading chamber having beencreated again, the loading chamber may be pressurized to atmosphericpressure without disturbing the vacuum in the remainder of the vacuumchamber. The chamber cover may be removed, and the prepared sample maybe removed from the apparatus along with the shield to which it waspreviously adhered. A microscope may be fitted with a shield retentionstage so that the prepared sample and shield may be retained and therebythe prepared region of the sample may be observed in the microscope.After observation, the user may decide that additional samplepreparation is needed. Since the sample is still durably adhered to theshield, it is a simple matter to return the sample and shield to thevacuum chamber for additional processing. The datum features on both theshield and the shield retention stage ensure that the shield may beretained in substantially the same position and orientation each timethe sample is processed in the apparatus. A kit comprising a shieldretention stage 40 with a plurality of datum features 70 a, 70 c, and 70e, shield retention means 42, and at least one shield 60 with aplurality of datum features 70 b, 70 d, and 70 f may be supplied forfitting to a microscope. Such a kit facilitates the microscopicobservation of samples prepared in the ion beam sample preparationapparatus 2.

Turning now to FIG. 14A, illustrated is a schematic cross-sectional viewof an embodiment of an ion beam sample preparation apparatus 2 adaptedto control the temperature of shield retention stage 40. The embodimentof FIG. 14A is shown comprising: a vacuum chamber 10 in which a samplemay be prepared by an ion beam irradiating means 20; a removable andreplaceable chamber cover 18, which, when removed from chamber 10,allows access for sample and shield loading; a first pumping manifold 92a and a pumping means 90, which together bring vacuum chamber 10 tovacuum levels appropriate for ion beam milling; a shield retention stage40 and a shield retention means 42, the shield retention means 42 beingshown in FIG. 14A in a shield retaining position; a retention stagelifting means 100 which is coupled to said shield retention stage 40; alift drive 102 operably coupled to said retention stage lifting means100, wherein the shield retention stage may be moved between a retentionstage loading position 104 as shown in FIG. 14A and a retention stageprocessing position 106 as shown in FIG. 14B, and vacuum seal 56, whichallows the retention stage lifting means to move up and down whilemaintaining vacuum seal between vacuum chamber 10 and the outsideatmosphere.

The apparatus of FIG. 14A is shown further comprising: a thermaltransfer member 80, which is in thermally conductive contact with shieldretention stage 40, and heat sink means 84, which facilitates heatexchange between thermal transfer member 80 and a heat exchange fluid orgas. When shield retention means 42 is in the shield retaining position,it urges thermally conductive contact between shield 60 and shieldretention stage 40, thereby facilitating heat exchange between shieldand shield retention stage. When shield retention stage 40 is raised toretention stage loading position 104 a loading chamber 16 is created.When in the retention stage loading position 104, vacuum sealingfeatures of the shield retention stage 40 engage with vacuum sealingfeatures of the vacuum chamber 10 and function to isolate said vacuumchamber from the outside atmosphere. Second pumping manifold 92 b andpumping means 90 may be used to evacuate loading chamber 16 inpreparation for lowering the shield retention stage into the retentionstage processing position. In a preferred embodiment, when chamber cover18 is in place to seal the loading chamber from the outside atmosphere,the volume of loading chamber 16 is substantially smaller than thevolume of vacuum chamber 10.

With continuing reference to FIG. 14A, the ion beam preferably comprisesnoble gas ions. Elements used for the ion beam may include but are notlimited to: Argon, Xenon, and Krypton. The ion beam may also comprise amixture of ions and neutrals. Heat sink means 84 may use gaseousnitrogen, liquid nitrogen, other gases, or other liquids as a heatabsorbing medium. Heat sink means 84 may additionally comprisetemperature control means capable of substantially maintaining thermaltransfer member 80 at a predetermined temperature. Shield retentionstage 40 of FIG. 14A and FIG. 14B has the same features and functionspossessed by shield retention stage 40 shown in FIG. 1A, FIG. 1B, FIG.1C, FIG. 2, FIG. 3A, FIG. 3B, FIG. 4, FIG. 5A, FIG. 5B, and FIG. 6. Inaddition, shield 60 of FIG. 14A and FIG. 14B has the same features,functions, and aspects possessed by shield 60 shown in figures FIG. 3A,FIG. 3B, FIG. 5A, FIG. 5B, FIG. 6, FIG. 7A, FIG. 7B, FIG. 8A, and FIG.8B. In a preferred embodiment of shield 60, a material with good thermalconductivity can be used to improve thermal transfer between shield andthe shield retention stage, said material including, but not limited to,a substantially non-magnetic metal. FIG. 13A and FIG. 13B show otherpreferred embodiments of shield 60 in which a material with good thermalconductivity can be used as a core material to improve thermal transferbetween shield and the shield retention stage, and a substantiallynon-magnetic material with low sputtering-yield may be used as acladding material over the core material, whereby the cladding materialforms at least part of the shielding surface 61 of shield 60.

The apparatus of FIG. 14B shows the same apparatus as FIG. 14A. However,in FIG. 14B the retention stage lifting means 104 and lift drive 102have operated to move shield retention stage 40 into retention stageprocessing position 106. When in the retention stage processingposition, shield retention stage 40 is disposed in vacuum chamber 10 ina predetermined position and orientation with respect to central ionbeam axis 22.

In the apparatus of FIG. 14A and FIG. 14B, the shield retention stage 40datum features allow the interchangeable use of shield 60 previouslydescribed. By means of the two positions provided by the shieldretention means, namely shield retaining position 46 as shown in FIG.3B, and shield releasing position 48 as shown in FIG. 4, a shield may beremovable and replaceably secured in shield retention stage 40. A samplethat has been durably adhered to shield 60 may be processed, removed,and then reprocessed by simply placing it in the shield retainingposition and preparing the sample again in the ion beam. The datumfeatures on both shield and shield retention stage assure that theshield may be positioned in a substantially identical position andorientation multiple times.

Use of the apparatus of FIG. 14A and FIG. 14B may proceed according toall of the steps disclosed for the use of the apparatus of FIG. 1A, FIG.1B, FIG. 1C, and FIG. 2. However, the thermal transfer member and heatsink means shown in the embodiment of FIG. 14A and FIG. 14B give theuser additional capabilities. In the embodiment of FIG. 14A and FIG. 14Bthe thermal control works particularly well in concert with theretention stage lifting means, lift drive, and isolated loading chamberthat is created when in the retention stage loading position. It may bethe case that a sample is prepared in the ion beam while the sample isheld at low temperature. Such a temperature may be below the dew pointof the local atmosphere immediately outside of the apparatus. If theshield retention stage is at a temperature below the local dew point,then exposing it to the atmosphere during loading and unloading mayresult in water condensation in the loading chamber. Such watercondensation would spoil the vacuum conditions maintained in the vacuumchamber if the wet retention stage were moved into the vacuum chamber.In addition, condensation, if allowed to form on the sample, may ruinthe sample. The heat sink means may be beneficially used to bring thetemperature of the shield retention stage above the local dew pointbefore the user takes the chamber cover off to access the shieldretention stage. The retention stage lifting means creates anotherbenefit in that the creation of the loading chamber significantlyreduces the volume of the apparatus that must be exposed to the ambientatmosphere during sample loading and unloading. This is a tremendoustime saver whenever the temperature of the shield retention stage mustbe raised or lowered to match the ambient atmospheric temperature.

Turning now to FIG. 15A and FIG. 15B, illustrated is a schematiccross-sectional view of another embodiment of an ion beam samplepreparation apparatus 2. The apparatus of FIG. 15A and FIG. 15B isadapted to control the temperature of shield retention stage 40 by meansof a different configuration than the embodiment of FIG. 14A and 14B.The embodiment of FIG. 15A is shown comprising: a vacuum chamber 10, inwhich a sample may be prepared by an ion beam irradiating means 20; aremovable and replaceable chamber cover 18, which, when removed fromchamber 10, allows access for sample and shield loading; a first pumpingmanifold 92 a and a pumping means 90, which together bring vacuumchamber 10 to vacuum levels appropriate for ion beam milling; a shieldretention stage 40 and a shield retention means 42, the shield retentionmeans 42 being shown in FIG. 15A in a shield retaining position; aretention stage lifting means 100, which is coupled to said shieldretention stage 40; a lift drive 102, operably coupled to said retentionstage lifting means 100, wherein the shield retention stage may be movedbetween a retention stage loading position 104, as shown in FIG. 15A,and a retention stage processing position 106, as shown in FIG. 15B, andvacuum seal 56, which allows the retention stage lifting means to moveup and down while maintaining vacuum seal between vacuum chamber 10 andthe outside atmosphere. When shield retention stage 40 is raised toretention stage loading position 104, a loading chamber 16 is created.The apparatus of FIG. 15A and FIG. 15B is shown further comprising athermal transfer member 80 and a heat sink means 84, which togetherfacilitate heat exchange between thermal transfer member 80 and heatsink means 84.

The apparatus of both FIG. 15A and FIG. 15B are shown with a sample 8durably adhered to a shield 60. The sample and shield combination areshown held in a shield retaining position of the shield retention means42. Shield retention stage 40 and shield 60 work in the same way andhave the same features and aspects as the shield retention stage andshield shown in FIG. 1A, FIG. 1B, FIG. 1C, FIG. 2, FIG. 3A, FIG. 3B,FIG. 4, FIG. 5A, FIG. 5B, FIG. 6, FIG. 7A, FIG. 7B, FIG. 8A, FIG. 8B,all previously described in the present disclosure. The shield retentionstage of FIG. 15A and FIG. 15B has additional features that allow it toengage, in thermally conductive contact, with thermal transfer member 80when the retention stage lifting means is in retention stage processingposition 106. Also, the shield retention stage of FIG. 15A and FIG. 15Bhas features that allow it to disengage from thermally conductivecontact with thermal transfer member 80 when the retention stage liftingmeans 100 is in retention stage loading position 104.

With continuing reference to FIG. 15A and FIG. 15B, when shieldretention means 42 is in the shield retaining position, it urgesthermally conductive contact between shield 60 and shield retentionstage 40, thereby facilitating heat exchange between shield and shieldretention stage. When retention stage lifting means is in the retentionstage loading position 104 there is no thermally conductive contactbetween shield retention stage 40 and thermal transfer member 80.Furthermore, when in retention stage loading position 104, the shieldretention stage may be in thermally conductive contact with a portion ofvacuum chamber 10. Thermally conductive contact may allow the shieldretention stage to exchange heat with the contacting portion of thevacuum chamber and thereby the sample, shield, and shield retentionstage may approach the same temperature as exists in the contactingportion of the vacuum chamber.

When in the retention stage loading position 104, vacuum sealingfeatures of the shield retention stage 40 engage with vacuum sealingfeatures of the vacuum chamber 10 and function to isolate said vacuumchamber from the outside atmosphere. Second pumping manifold 92 b andpumping means 90 may be used to evacuate loading chamber 16 inpreparation for lowering the shield retention stage into the retentionstage processing position. In a preferred embodiment, when chamber cover18 is in place to seal the loading chamber from the outside atmosphere,the volume of loading chamber 16 is substantially smaller than thevolume of vacuum chamber 10.

FIG. 15B shows the apparatus of FIG. 15A after the retention stagelifting means 100 and lift drive 102 have operated to move to theretention stage processing position 106. In this position, thermaltransfer member 80 is in thermally conductive contact with shieldretention stage 40. Heat sink means 84 may operate in this position toexchange heat through thermal transfer member 80, and thereby affect thetemperature of shield retention stage 40. The thermally conductivecontact established between shield 60 and shield retention stage 40 whenthe shield is held in the shield retaining position completes thethermal circuit and allows for the exchange of heat between heat sinkmeans 84 and shield 60. In preferred embodiments, heat sink means 84 mayuse gaseous or liquid nitrogen as a heat exchange medium.

Use of the apparatus of FIG. 15A and FIG. 15B may proceed according toall of the steps disclosed for the use of the apparatus of FIG. 1A, FIG.1B, FIG. 1C, and FIG. 2. However, the thermal transfer member and heatsink means shown in the embodiment of FIG. 15A and FIG. 15B give theuser additional capabilities. In the embodiment of FIG. 15A and FIG. 15Bthe thermal control works particularly well in concert with theretention stage lifting means, lift drive, and isolated loading chamberthat is created when in the retention stage loading position. It may bethe case that a sample is prepared in the ion beam while the sample isheld at low temperature. Such a temperature may be below the dew pointof the local atmosphere immediately outside of the apparatus. If theshield retention stage is at a temperature below the local dew point,then exposing it to the atmosphere during loading and unloading mayresult in water condensation in the loading chamber. Such watercondensation would spoil the vacuum conditions maintained in the vacuumchamber if the wet retention stage were moved into the vacuum chamber.In addition, condensation, if allowed to form on the sample, may ruinthe sample. After the sample has been processed in the ion beam, it maybe moved by the retention stage lifting means and lift drive into theretention stage loading position. In this position the shield retentionstage is in thermally conductive contact with a portion of the vacuumchamber. Since the thermal transfer member is no longer in contact withthe shield retention stage, the temperature of the shield retentionstage is free to rise to the temperature of that portion of the vacuumchamber. Since the temperature of the vacuum chamber is at about thesame temperature as the local atmosphere, the shield retention stage,shield, and sample will approach the temperature of the localatmosphere. The thermally conductive contact between the vacuum chamberand the shield retention stage when in the retention stage loadingposition provides an efficient way to warm up a sample that has beenpreviously cooled while in the retention stage processing position. Whenthe sample, shield, and shield retention stage have warmed upsufficiently, the loading chamber may be re-pressurized to ambientconditions, the chamber cover may be removed, and the shield and samplecombination may be removed from the apparatus for microscopicobservation elsewhere.

Although the present invention has been described in considerable detailwith reference to certain preferred versions thereof, other versions arepossible. For example, it may be desirable to combine features shown invarious embodiments into a single embodiment. Also, it may be thatcertain preferred versions have alternatives that may be suitablysubstituted and achieve similar performance in various embodiments. Forexample, the chamber cover used to access the loading chamber of theapparatus may satisfy the needed functionality equally well whether itbe tethered to the apparatus, attached to the apparatus via hinge, orcapable of being entirely removed from the apparatus. These and otherequivalents will be readily recognized by those skilled in the art.Therefore, the spirit and scope of the appended claims should not belimited to the description of the preferred versions contained herein.

Any element in a claim that does not explicitly state “means for”performing a specified function, or “step for” performing a specificfunction, is not to be interpreted as a “means” or “step” clause asspecified in 35 U.S.C. Section 112, Paragraph 6. In particular, the useof “step of” in the claims herein is not intended to invoke theprovisions of 35 U.S.C. Section 112, Paragraph 6.

1. An ion beam sample preparation apparatus comprising: a) an ion beamirradiating means disposed in a vacuum chamber and directing an ion beamtoward a shield retention stage; b) the shield retention stage beingdisposed in the vacuum chamber; said shield retention stage comprising:i) a first datum feature; ii) a second datum feature; iii) a shieldretention means having at least a shield releasing position and a shieldretaining position; c) a retention stage lifting means coupled to saidshield retention stage and configured to move said shield retentionstage between a retention stage loading position and a retention stageprocessing position, characterized in that when the retention stagelifting means is in said retention stage loading position asubstantially vacuum-tight loading chamber is created between the shieldretention stage and a portion of the vacuum chamber, and furthercharacterized in that when the retention stage lifting means is in saidretention stage loading position a substantially vacuum-tight seal iscreated between the loading chamber and the portion of the vacuumchamber in which the ion beam irradiating means is disposed; d) a liftdrive coupled to said retention stage lifting means and operable to movesaid retention stage lifting means between said retention stage loadingposition and said retention stage processing position; e) a removableand replaceable chamber cover disposed to allow access to said loadingchamber when said retention stage lifting means is held in saidretention stage loading position, characterized in that said chambercover provides a substantially vacuum-tight seal when in place on saidvacuum chamber; f) a shield having at least a rigid planar portion,removably and replaceably held in said shield retention stage, saidshield further comprising: i) a proximal sample surface configured todurably adhere the sample to the shield; ii) a first shielding surfacedisposed in the path of the ion beam and positioned to shield a portionof the ion beam directed at the sample when said shield is held in theshield retaining position of the shield retention means and theretention stage lifting means is held in the retention stage processingposition; iii) a third datum feature formed integrally with said shield,wherein said shield retention means in said shield retaining positionurges said third datum feature to abut said first datum feature; and,iv) a fourth datum feature formed integrally with said shield, whereinsaid shield retention means in said shield retaining position urges saidfourth datum feature to abut said second datum feature; g) a vacuum pumpmeans operably connected to both a first pumping manifold and a secondpumping manifold, wherein the first pumping manifold is configured toevacuate said vacuum chamber, and wherein the second pumping manifold isconfigured to evacuate said loading chamber when said retention stagelifting means is in said retention stage loading position.
 2. Theapparatus of claim 1 wherein the shield retention stage furthercomprises a fifth datum feature, and the shield further comprises asixth datum feature formed integrally with the shield, wherein theshield retention means in said shield retaining position urges saidsixth datum feature to abut said fifth datum feature.
 3. The apparatusof claim 1 wherein the first shielding surface meets said proximalsample surface at an angle of less than about 90 degrees and more thanabout 80 degrees.
 4. The apparatus of claim 1 wherein the firstshielding surface meets said proximal sample surface at an angle of lessthan about 87 degrees and more than about 83 degrees.
 5. The apparatusof claim 1 wherein the first shielding surface is made of non-magneticmaterial having low sputtering-yield.
 6. The apparatus of claim 1wherein at least a portion of the first shielding surface is made oftantalum or titanium.
 7. The apparatus of claim 1 wherein the thirddatum feature is a datum surface and at least a portion of said datumsurface is coextensive with at least a portion of said proximal samplesurface.
 8. The apparatus of claim 1 wherein the proximal sample surfacehas at least one recessed portion configured for the flowing of adhesivebetween the shield and the sample.
 9. The apparatus of claim 1 whereinthe shield further comprises a sample clamping means coupled to theshield and configured to hold the sample against said proximal samplesurface.
 10. The apparatus of claim 1 wherein the shield furthercomprises: a) a second shielding surface having a portion disposed inthe path of a portion of the ion beam; b) a shield edge formed where thefirst shielding surface meets the proximal sample surface; and c) avisible alignment mark on the second shielding surface, configured suchthat the location of said visible alignment mark is in a predeterminedrelationship to the region where the ion beam impinges on said shieldedge when said shield is held in the shield retaining position of theshield retention means.
 11. The apparatus of claim 1 wherein the shieldis made of a cladding material joined to a core material such that aportion of the cladding material forms at least a portion of the firstshielding surface, and a portion of the core material forms said thirddatum feature of the shield and said fourth datum feature of the shield.12. The apparatus of claim 11 wherein the cladding material is made ofnon-magnetic material having low sputtering-yield.
 13. The apparatus ofclaim 12 wherein at least a portion of the cladding material is tantalumor titanium.
 14. An ion beam sample preparation apparatus comprising: a)an ion beam irradiating means disposed in a vacuum chamber and directingan ion beam toward a shield retention stage; b) the shield retentionstage being disposed in the vacuum chamber; said shield retention stagecomprising: i) a first datum feature; ii) a second datum feature; iii) ashield retention means having at least a shield releasing position and ashield retaining position; c) a retention stage lifting means coupled tosaid shield retention stage and configured to move said shield retentionstage between a retention stage loading position and a retention stageprocessing position, characterized in that when the retention stagelifting means is in said retention stage loading position asubstantially vacuum-tight loading chamber is created between the shieldretention stage and a portion of the vacuum chamber, and furthercharacterized in that when the retention stage lifting means is in saidretention stage loading position a substantially vacuum-tight seal iscreated between the loading chamber and the portion of the vacuumchamber in which the ion beam irradiating means is disposed; d) a liftdrive coupled to said retention stage lifting means and operable to movesaid retention stage lifting means between said retention stage loadingposition and said retention stage processing position; e) a removableand replaceable chamber cover disposed to allow access to said loadingchamber when said retention stage lifting means is held in saidretention stage loading position, characterized in that said chambercover provides a substantially vacuum-tight seal when in place on saidvacuum chamber; f) a shield having at least a rigid planar portion,removably and replaceably held in said shield retention stage, saidshield further comprising: i) a proximal sample surface configured todurably adhere the sample to the shield; ii) a first shielding surfacedisposed in the path of the ion beam and positioned to shield a portionof the ion beam directed at the sample when said shield is held in theshield retaining position of the shield retention means and theretention stage lifting means is held in the retention stage processingposition; iii) a third datum feature formed integrally with said shield,wherein said shield retention means in said shield retaining positionurges said third datum feature to abut in thermally conductive contactsaid first datum feature; and iv) a fourth datum feature formedintegrally with said shield, wherein said shield retention means in saidshield retaining position urges said fourth datum feature to abut saidsecond datum feature g) a vacuum pump means operably connected to both afirst pumping manifold and a second pumping manifold, wherein the firstpumping manifold is configured to evacuate said vacuum chamber, andwherein the second pumping manifold is configured to evacuate saidloading chamber when said retention stage lifting means is in saidretention stage loading position; h) a thermal transfer member inthermally conductive contact with the shield retention stage; i) a heatsink means configured to conduct heat away from said thermal transfermember.
 15. The apparatus of claim 14 wherein the shield retention stagefurther comprises a fifth datum feature, and the shield furthercomprises a sixth datum feature formed integrally with the shield,wherein the shield retention means in said shield retaining positionurges said sixth datum feature to abut said fifth datum feature.
 16. Theapparatus of claim 14 wherein the first shielding surface meets saidproximal sample surface at an angle of less than about 90 degrees andmore than about 80 degrees.
 17. The apparatus of claim 14 wherein thefirst shielding surface meets said proximal sample surface at an angleof less than about 87 degrees and more than about 83 degrees.
 18. Theapparatus of claim 14 wherein the first shielding surface is made ofnon-magnetic material with low sputtering-yield.
 19. The apparatus ofclaim 14 wherein at least a portion of the first shielding surface ismade of tantalum or titanium.
 20. The apparatus of claim 14 wherein thethird datum feature is a datum surface and a portion of said datumsurface is coextensive with a portion of said proximal sample surface.21. The apparatus of claim 14 wherein the proximal sample surface has atleast one recessed portion configured for the flowing of adhesivebetween the shield and the sample.
 22. The apparatus of claim 14 whereinthe shield further comprises a sample clamping means coupled to theshield and configured to hold the sample against said proximal samplesurface.
 23. The apparatus of claim 14 wherein the shield furthercomprises: a) a second shielding surface having a portion disposed inthe path of a portion of the ion beam; b) a visible alignment mark onthe second shielding surface, configured such that the location of saidvisible alignment mark is in a predetermined relationship to the regionwhere the ion beam impinges on said shield edge when said shield is heldin the shield retaining position of the shield retention means.
 24. Theapparatus of claim 14 wherein the heat sink means is configured to usenitrogen to conduct heat away from the thermal transfer member.
 25. Theapparatus of claim 14 wherein the shield is made of a material havinghigh thermal conductivity.
 26. The apparatus of claim 14 wherein theshield is made of a cladding material joined to a core material suchthat a portion of the cladding material forms at least a portion of thefirst shielding surface, and a portion of the core material forms thethird and fourth datum features of the shield.
 27. The apparatus ofclaim 26 wherein the core material comprises copper.
 28. An ion beamsample preparation apparatus comprising: a) an ion beam irradiatingmeans disposed in a vacuum chamber and directing an ion beam toward ashield retention stage; b) the shield retention stage being disposed inthe vacuum chamber; said shield retention stage comprising: i) a firstdatum feature; ii) a second datum feature; iii) a shield retention meanshaving at least a shield releasing position and a shield retainingposition; c) a retention stage lifting means coupled to said shieldretention stage and configured to move said shield retention stagebetween a retention stage loading position and a retention stageprocessing position, characterized in that when the retention stagelifting means is in said retention stage loading position asubstantially vacuum-tight loading chamber is created between the shieldretention stage and a portion of the vacuum chamber, furthercharacterized in that when the retention stage lifting means is in saidretention stage loading position, a substantially vacuum-tight seal iscreated between the loading chamber and the portion of the vacuumchamber in which the ion beam irradiating means is disposed, and furthercharacterized in that when the retention stage lifting means is in saidretention stage loading position said shield retention stage is inthermally conductive contact with a portion of said vacuum chamber; d) alift drive coupled to said retention stage lifting means and operable tomove said retention stage lifting means between said retention stageloading position and said retention stage processing position; e) aremovable and replaceable chamber cover disposed to allow access to saidloading chamber when said retention stage lifting means is held in saidretention stage loading position, characterized in that said chambercover provides a substantially vacuum-tight seal when in place on saidvacuum chamber; f) a shield having at least a rigid planar portion,removably and replaceably held in said shield retention stage, saidshield further comprising: i) a proximal sample surface configured todurably adhere the sample to the shield; ii) a first shielding surfacedisposed in the path of the ion beam and positioned to shield a portionof the ion beam directed at the sample when said shield is held in theshield retaining position of the shield retention means and theretention stage lifting means is held in the retention stage processingposition; iii) a third datum feature formed integrally with said shield,wherein said shield retention means in said shield retaining positionurges said third datum feature to abut in thermally conductive contactsaid first datum feature; and iv) a fourth datum feature formedintegrally with said shield, wherein said shield retention means in saidshield retaining position urges said fourth datum feature to abut saidsecond datum feature g) a vacuum pump means operably connected to both afirst pumping manifold and a second pumping manifold, wherein the firstpumping manifold is configured to evacuate said vacuum chamber, andwherein the second pumping manifold is configured to evacuate saidloading chamber when said retention stage lifting means is in saidretention stage loading position; h) a thermal transfer member disposedso that said thermal transfer member is in thermally conductive contactwith the shield retention stage when said retention stage lifting meansis held in said retention stage processing position, and furtherdisposed so that said thermal transfer member is not in thermallyconductive contact with the shield retention stage when said retentionstage lifting means is held in said retention stage loading position; i)a heat sink means configured to conduct heat away from said thermaltransfer member.
 29. The apparatus of claim 28 wherein the shieldretention stage further comprises a fifth datum feature, and the shieldfurther comprises a sixth datum feature formed integrally with theshield, wherein the shield retention means in said shield retainingposition urges said sixth datum feature to abut said fifth datumfeature.
 30. The apparatus of claim 28 wherein the first shieldingsurface meets said proximal sample surface at an angle of less thanabout 90 degrees and more than about 80 degrees.
 31. The apparatus ofclaim 28 wherein the first shielding surface meets said proximal samplesurface at an angle of less than about 87 degrees and more than about 83degrees.
 32. The apparatus of claim 28 wherein the first shieldingsurface is made of non-magnetic material with low sputtering-yield. 33.The apparatus of claim 28 wherein at least a portion of the firstshielding surface is made of tantalum or titanium.
 34. The apparatus ofclaim 28 wherein the third datum feature is a datum surface and aportion of said datum surface is coextensive with a portion of saidproximal sample surface.
 35. The apparatus of claim 28 wherein theproximal sample surface has at least one recessed portion configured forthe flowing of adhesive between the shield and the sample.
 36. Theapparatus of claim 28 wherein the shield further comprises a sampleclamping means coupled to the shield and configured to hold the sampleagainst said proximal sample surface.
 37. The apparatus of claim 28wherein the shield further comprises: a) a second shielding surfacehaving a portion disposed in the path of a portion of the ion beam; b) avisible alignment mark on the second shielding surface, configured suchthat the location of said visible alignment mark is in a predeterminedrelationship to the region where the ion beam impinges on said shieldedge when said shield is held in the shield retaining position of theshield retention means.
 38. The apparatus of claim 28 wherein the heatsink means is configured to use nitrogen to conduct heat away from thethermal transfer member.
 39. The apparatus of claim 28 wherein theshield is made of a material having high thermal conductivity.
 40. Theapparatus of claim 28 wherein the shield is made of a cladding materialjoined to a core material such that a portion of the cladding materialforms at least a portion of the first shielding surface, and a portionof the core material forms the third and fourth datum features of theshield.
 41. The apparatus of claim 40 wherein the core materialcomprises copper.